Documentation/networking/e1000e.txt - arm/linux - Git at Google


            
            Linux* Driver for Intel(R) Ethernet Network Connection

            
            ======================================================


            Intel Gigabit Linux driver.

            
            Copyright(c) 1999 - 2013 Intel Corporation.


            Contents

            
            ========


            - Identifying Your Adapter

            
            - Command Line Parameters

            
            - Additional Configurations

            
            - Support


            Identifying Your Adapter

            
            ========================


            The e1000e driver supports all PCI Express Intel(R) Gigabit Network

            
            Connections, except those that are 82575, 82576 and 82580-based*.


            * NOTE: The Intel(R) PRO/1000 P Dual Port Server Adapter is supported by

            
              the e1000 driver, not the e1000e driver due to the 82546 part being used

            
              behind a PCI Express bridge.


            For more information on how to identify your adapter, go to the Adapter &

            
            Driver ID Guide at:


                http://support.intel.com/support/go/network/adapter/idguide.htm


            For the latest Intel network drivers for Linux, refer to the following

            
            website.  In the search field, enter your adapter name or type, or use the

            
            networking link on the left to search for your adapter:


                http://support.intel.com/support/go/network/adapter/home.htm


            Command Line Parameters

            
            =======================


            The default value for each parameter is generally the recommended setting,

            
            unless otherwise noted.


            NOTES:  For more information about the InterruptThrottleRate,

            
                    RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay

            
                    parameters, see the application note at:

            
                    http://www.intel.com/design/network/applnots/ap450.htm


            InterruptThrottleRate

            
            ---------------------

            
            Valid Range:   0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative,

            
                                               4=simplified balancing)

            
            Default Value: 3


            The driver can limit the amount of interrupts per second that the adapter

            
            will generate for incoming packets. It does this by writing a value to the

            
            adapter that is based on the maximum amount of interrupts that the adapter

            
            will generate per second.


            Setting InterruptThrottleRate to a value greater or equal to 100

            
            will program the adapter to send out a maximum of that many interrupts

            
            per second, even if more packets have come in. This reduces interrupt

            
            load on the system and can lower CPU utilization under heavy load,

            
            but will increase latency as packets are not processed as quickly.


            The default behaviour of the driver previously assumed a static

            
            InterruptThrottleRate value of 8000, providing a good fallback value for

            
            all traffic types, but lacking in small packet performance and latency.

            
            The hardware can handle many more small packets per second however, and

            
            for this reason an adaptive interrupt moderation algorithm was implemented.


            The driver has two adaptive modes (setting 1 or 3) in which

            
            it dynamically adjusts the InterruptThrottleRate value based on the traffic

            
            that it receives. After determining the type of incoming traffic in the last

            
            timeframe, it will adjust the InterruptThrottleRate to an appropriate value

            
            for that traffic.


            The algorithm classifies the incoming traffic every interval into

            
            classes.  Once the class is determined, the InterruptThrottleRate value is

            
            adjusted to suit that traffic type the best. There are three classes defined:

            
            "Bulk traffic", for large amounts of packets of normal size; "Low latency",

            
            for small amounts of traffic and/or a significant percentage of small

            
            packets; and "Lowest latency", for almost completely small packets or

            
            minimal traffic.


            In dynamic conservative mode, the InterruptThrottleRate value is set to 4000

            
            for traffic that falls in class "Bulk traffic". If traffic falls in the "Low

            
            latency" or "Lowest latency" class, the InterruptThrottleRate is increased

            
            stepwise to 20000. This default mode is suitable for most applications.


            For situations where low latency is vital such as cluster or

            
            grid computing, the algorithm can reduce latency even more when

            
            InterruptThrottleRate is set to mode 1. In this mode, which operates

            
            the same as mode 3, the InterruptThrottleRate will be increased stepwise to

            
            70000 for traffic in class "Lowest latency".


            In simplified mode the interrupt rate is based on the ratio of TX and

            
            RX traffic.  If the bytes per second rate is approximately equal, the

            
            interrupt rate will drop as low as 2000 interrupts per second.  If the

            
            traffic is mostly transmit or mostly receive, the interrupt rate could

            
            be as high as 8000.


            Setting InterruptThrottleRate to 0 turns off any interrupt moderation

            
            and may improve small packet latency, but is generally not suitable

            
            for bulk throughput traffic.


            NOTE:  InterruptThrottleRate takes precedence over the TxAbsIntDelay and

            
                   RxAbsIntDelay parameters.  In other words, minimizing the receive

            
                   and/or transmit absolute delays does not force the controller to

            
                   generate more interrupts than what the Interrupt Throttle Rate

            
                   allows.


            NOTE:  When e1000e is loaded with default settings and multiple adapters

            
                   are in use simultaneously, the CPU utilization may increase non-

            
                   linearly.  In order to limit the CPU utilization without impacting

            
                   the overall throughput, we recommend that you load the driver as

            
                   follows:


                       modprobe e1000e InterruptThrottleRate=3000,3000,3000


                   This sets the InterruptThrottleRate to 3000 interrupts/sec for

            
                   the first, second, and third instances of the driver.  The range

            
                   of 2000 to 3000 interrupts per second works on a majority of

            
                   systems and is a good starting point, but the optimal value will

            
                   be platform-specific.  If CPU utilization is not a concern, use

            
                   RX_POLLING (NAPI) and default driver settings.


            RxIntDelay

            
            ----------

            
            Valid Range:   0-65535 (0=off)

            
            Default Value: 0


            This value delays the generation of receive interrupts in units of 1.024

            
            microseconds.  Receive interrupt reduction can improve CPU efficiency if

            
            properly tuned for specific network traffic.  Increasing this value adds

            
            extra latency to frame reception and can end up decreasing the throughput

            
            of TCP traffic.  If the system is reporting dropped receives, this value

            
            may be set too high, causing the driver to run out of available receive

            
            descriptors.


            CAUTION:  When setting RxIntDelay to a value other than 0, adapters may

            
                      hang (stop transmitting) under certain network conditions.  If

            
                      this occurs a NETDEV WATCHDOG message is logged in the system

            
                      event log.  In addition, the controller is automatically reset,

            
                      restoring the network connection.  To eliminate the potential

            
                      for the hang ensure that RxIntDelay is set to 0.


            RxAbsIntDelay

            
            -------------

            
            Valid Range:   0-65535 (0=off)

            
            Default Value: 8


            This value, in units of 1.024 microseconds, limits the delay in which a

            
            receive interrupt is generated.  Useful only if RxIntDelay is non-zero,

            
            this value ensures that an interrupt is generated after the initial

            
            packet is received within the set amount of time.  Proper tuning,

            
            along with RxIntDelay, may improve traffic throughput in specific network

            
            conditions.


            TxIntDelay

            
            ----------

            
            Valid Range:   0-65535 (0=off)

            
            Default Value: 8


            This value delays the generation of transmit interrupts in units of

            
            1.024 microseconds.  Transmit interrupt reduction can improve CPU

            
            efficiency if properly tuned for specific network traffic.  If the

            
            system is reporting dropped transmits, this value may be set too high

            
            causing the driver to run out of available transmit descriptors.


            TxAbsIntDelay

            
            -------------

            
            Valid Range:   0-65535 (0=off)

            
            Default Value: 32


            This value, in units of 1.024 microseconds, limits the delay in which a

            
            transmit interrupt is generated.  Useful only if TxIntDelay is non-zero,

            
            this value ensures that an interrupt is generated after the initial

            
            packet is sent on the wire within the set amount of time.  Proper tuning,

            
            along with TxIntDelay, may improve traffic throughput in specific

            
            network conditions.


            Copybreak

            
            ---------

            
            Valid Range:   0-xxxxxxx (0=off)

            
            Default Value: 256


            Driver copies all packets below or equaling this size to a fresh RX

            
            buffer before handing it up the stack.


            This parameter is different than other parameters, in that it is a

            
            single (not 1,1,1 etc.) parameter applied to all driver instances and

            
            it is also available during runtime at

            
            /sys/module/e1000e/parameters/copybreak


            SmartPowerDownEnable

            
            --------------------

            
            Valid Range: 0-1

            
            Default Value:  0 (disabled)


            Allows PHY to turn off in lower power states. The user can set this parameter

            
            in supported chipsets.


            KumeranLockLoss

            
            ---------------

            
            Valid Range: 0-1

            
            Default Value: 1 (enabled)


            This workaround skips resetting the PHY at shutdown for the initial

            
            silicon releases of ICH8 systems.


            IntMode

            
            -------

            
            Valid Range: 0-2 (0=legacy, 1=MSI, 2=MSI-X)

            
            Default Value: 2


            Allows changing the interrupt mode at module load time, without requiring a

            
            recompile. If the driver load fails to enable a specific interrupt mode, the

            
            driver will try other interrupt modes, from least to most compatible.  The

            
            interrupt order is MSI-X, MSI, Legacy.  If specifying MSI (IntMode=1)

            
            interrupts, only MSI and Legacy will be attempted.


            CrcStripping

            
            ------------

            
            Valid Range: 0-1

            
            Default Value: 1 (enabled)


            Strip the CRC from received packets before sending up the network stack.  If

            
            you have a machine with a BMC enabled but cannot receive IPMI traffic after

            
            loading or enabling the driver, try disabling this feature.


            WriteProtectNVM

            
            ---------------

            
            Valid Range: 0,1

            
            Default Value: 1


            If set to 1, configure the hardware to ignore all write/erase cycles to the

            
            GbE region in the ICHx NVM (in order to prevent accidental corruption of the

            
            NVM). This feature can be disabled by setting the parameter to 0 during initial

            
            driver load.

            
            NOTE: The machine must be power cycled (full off/on) when enabling NVM writes

            
            via setting the parameter to zero. Once the NVM has been locked (via the

            
            parameter at 1 when the driver loads) it cannot be unlocked except via power

            
            cycle.


            Additional Configurations

            
            =========================


              Jumbo Frames

            
              ------------

            
              Jumbo Frames support is enabled by changing the MTU to a value larger than

            
              the default of 1500.  Use the ifconfig command to increase the MTU size.

            
              For example:


                   ifconfig eth<x> mtu 9000 up


              This setting is not saved across reboots.


              Notes:


              - The maximum MTU setting for Jumbo Frames is 9216.  This value coincides

            
                with the maximum Jumbo Frames size of 9234 bytes.


              - Using Jumbo frames at 10 or 100 Mbps is not supported and may result in

            
                poor performance or loss of link.


              - Some adapters limit Jumbo Frames sized packets to a maximum of

            
                4096 bytes and some adapters do not support Jumbo Frames.


              - Jumbo Frames cannot be configured on an 82579-based Network device, if

            
                MACSec is enabled on the system.


              ethtool

            
              -------

            
              The driver utilizes the ethtool interface for driver configuration and

            
              diagnostics, as well as displaying statistical information.  We

            
              strongly recommend downloading the latest version of ethtool at:


              http://ftp.kernel.org/pub/software/network/ethtool/


              NOTE: When validating enable/disable tests on some parts (82578, for example)

            
              you need to add a few seconds between tests when working with ethtool.


              Speed and Duplex

            
              ----------------

            
              Speed and Duplex are configured through the ethtool* utility. For

            
              instructions,  refer to the ethtool man page.


              Enabling Wake on LAN* (WoL)

            
              ---------------------------

            
              WoL is configured through the ethtool* utility. For instructions on

            
              enabling WoL with ethtool, refer to the ethtool man page.


              WoL will be enabled on the system during the next shut down or reboot.

            
              For this driver version, in order to enable WoL, the e1000e driver must be

            
              loaded when shutting down or rebooting the system.


              In most cases Wake On LAN is only supported on port A for multiple port

            
              adapters. To verify if a port supports Wake on Lan run ethtool eth<X>.


            Support

            
            =======


            For general information, go to the Intel support website at:


                www.intel.com/support/


            or the Intel Wired Networking project hosted by Sourceforge at:


                http://sourceforge.net/projects/e1000


            If an issue is identified with the released source code on the supported

            
            kernel with a supported adapter, email the specific information related

            
            to the issue to e1000-devel@lists.sf.net
	Linux* Driver for Intel(R) Ethernet Network Connection
	======================================================

	Intel Gigabit Linux driver.
	Copyright(c) 1999 - 2013 Intel Corporation.

	Contents
	========

	- Identifying Your Adapter
	- Command Line Parameters
	- Additional Configurations
	- Support

	Identifying Your Adapter
	========================

	The e1000e driver supports all PCI Express Intel(R) Gigabit Network
	Connections, except those that are 82575, 82576 and 82580-based*.

	* NOTE: The Intel(R) PRO/1000 P Dual Port Server Adapter is supported by
	the e1000 driver, not the e1000e driver due to the 82546 part being used
	behind a PCI Express bridge.

	For more information on how to identify your adapter, go to the Adapter &
	Driver ID Guide at:

	http://support.intel.com/support/go/network/adapter/idguide.htm

	For the latest Intel network drivers for Linux, refer to the following
	website. In the search field, enter your adapter name or type, or use the
	networking link on the left to search for your adapter:

	http://support.intel.com/support/go/network/adapter/home.htm

	Command Line Parameters
	=======================

	The default value for each parameter is generally the recommended setting,
	unless otherwise noted.

	NOTES: For more information about the InterruptThrottleRate,
	RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay
	parameters, see the application note at:
	http://www.intel.com/design/network/applnots/ap450.htm

	InterruptThrottleRate
	---------------------
	Valid Range: 0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative,
	4=simplified balancing)
	Default Value: 3

	The driver can limit the amount of interrupts per second that the adapter
	will generate for incoming packets. It does this by writing a value to the
	adapter that is based on the maximum amount of interrupts that the adapter
	will generate per second.

	Setting InterruptThrottleRate to a value greater or equal to 100
	will program the adapter to send out a maximum of that many interrupts
	per second, even if more packets have come in. This reduces interrupt
	load on the system and can lower CPU utilization under heavy load,
	but will increase latency as packets are not processed as quickly.

	The default behaviour of the driver previously assumed a static
	InterruptThrottleRate value of 8000, providing a good fallback value for
	all traffic types, but lacking in small packet performance and latency.
	The hardware can handle many more small packets per second however, and
	for this reason an adaptive interrupt moderation algorithm was implemented.

	The driver has two adaptive modes (setting 1 or 3) in which
	it dynamically adjusts the InterruptThrottleRate value based on the traffic
	that it receives. After determining the type of incoming traffic in the last
	timeframe, it will adjust the InterruptThrottleRate to an appropriate value
	for that traffic.

	The algorithm classifies the incoming traffic every interval into
	classes. Once the class is determined, the InterruptThrottleRate value is
	adjusted to suit that traffic type the best. There are three classes defined:
	"Bulk traffic", for large amounts of packets of normal size; "Low latency",
	for small amounts of traffic and/or a significant percentage of small
	packets; and "Lowest latency", for almost completely small packets or
	minimal traffic.

	In dynamic conservative mode, the InterruptThrottleRate value is set to 4000
	for traffic that falls in class "Bulk traffic". If traffic falls in the "Low
	latency" or "Lowest latency" class, the InterruptThrottleRate is increased
	stepwise to 20000. This default mode is suitable for most applications.

	For situations where low latency is vital such as cluster or
	grid computing, the algorithm can reduce latency even more when
	InterruptThrottleRate is set to mode 1. In this mode, which operates
	the same as mode 3, the InterruptThrottleRate will be increased stepwise to
	70000 for traffic in class "Lowest latency".

	In simplified mode the interrupt rate is based on the ratio of TX and
	RX traffic. If the bytes per second rate is approximately equal, the
	interrupt rate will drop as low as 2000 interrupts per second. If the
	traffic is mostly transmit or mostly receive, the interrupt rate could
	be as high as 8000.

	Setting InterruptThrottleRate to 0 turns off any interrupt moderation
	and may improve small packet latency, but is generally not suitable
	for bulk throughput traffic.

	NOTE: InterruptThrottleRate takes precedence over the TxAbsIntDelay and
	RxAbsIntDelay parameters. In other words, minimizing the receive
	and/or transmit absolute delays does not force the controller to
	generate more interrupts than what the Interrupt Throttle Rate
	allows.

	NOTE: When e1000e is loaded with default settings and multiple adapters
	are in use simultaneously, the CPU utilization may increase non-
	linearly. In order to limit the CPU utilization without impacting
	the overall throughput, we recommend that you load the driver as
	follows:

	modprobe e1000e InterruptThrottleRate=3000,3000,3000

	This sets the InterruptThrottleRate to 3000 interrupts/sec for
	the first, second, and third instances of the driver. The range
	of 2000 to 3000 interrupts per second works on a majority of
	systems and is a good starting point, but the optimal value will
	be platform-specific. If CPU utilization is not a concern, use
	RX_POLLING (NAPI) and default driver settings.

	RxIntDelay
	----------
	Valid Range: 0-65535 (0=off)
	Default Value: 0

	This value delays the generation of receive interrupts in units of 1.024
	microseconds. Receive interrupt reduction can improve CPU efficiency if
	properly tuned for specific network traffic. Increasing this value adds
	extra latency to frame reception and can end up decreasing the throughput
	of TCP traffic. If the system is reporting dropped receives, this value
	may be set too high, causing the driver to run out of available receive
	descriptors.

	CAUTION: When setting RxIntDelay to a value other than 0, adapters may
	hang (stop transmitting) under certain network conditions. If
	this occurs a NETDEV WATCHDOG message is logged in the system
	event log. In addition, the controller is automatically reset,
	restoring the network connection. To eliminate the potential
	for the hang ensure that RxIntDelay is set to 0.

	RxAbsIntDelay
	-------------
	Valid Range: 0-65535 (0=off)
	Default Value: 8

	This value, in units of 1.024 microseconds, limits the delay in which a
	receive interrupt is generated. Useful only if RxIntDelay is non-zero,
	this value ensures that an interrupt is generated after the initial
	packet is received within the set amount of time. Proper tuning,
	along with RxIntDelay, may improve traffic throughput in specific network
	conditions.

	TxIntDelay
	----------
	Valid Range: 0-65535 (0=off)
	Default Value: 8

	This value delays the generation of transmit interrupts in units of
	1.024 microseconds. Transmit interrupt reduction can improve CPU
	efficiency if properly tuned for specific network traffic. If the
	system is reporting dropped transmits, this value may be set too high
	causing the driver to run out of available transmit descriptors.

	TxAbsIntDelay
	-------------
	Valid Range: 0-65535 (0=off)
	Default Value: 32

	This value, in units of 1.024 microseconds, limits the delay in which a
	transmit interrupt is generated. Useful only if TxIntDelay is non-zero,
	this value ensures that an interrupt is generated after the initial
	packet is sent on the wire within the set amount of time. Proper tuning,
	along with TxIntDelay, may improve traffic throughput in specific
	network conditions.

	Copybreak
	---------
	Valid Range: 0-xxxxxxx (0=off)
	Default Value: 256

	Driver copies all packets below or equaling this size to a fresh RX
	buffer before handing it up the stack.

	This parameter is different than other parameters, in that it is a
	single (not 1,1,1 etc.) parameter applied to all driver instances and
	it is also available during runtime at
	/sys/module/e1000e/parameters/copybreak

	SmartPowerDownEnable
	--------------------
	Valid Range: 0-1
	Default Value: 0 (disabled)

	Allows PHY to turn off in lower power states. The user can set this parameter
	in supported chipsets.

	KumeranLockLoss
	---------------
	Valid Range: 0-1
	Default Value: 1 (enabled)

	This workaround skips resetting the PHY at shutdown for the initial
	silicon releases of ICH8 systems.

	IntMode
	-------
	Valid Range: 0-2 (0=legacy, 1=MSI, 2=MSI-X)
	Default Value: 2

	Allows changing the interrupt mode at module load time, without requiring a
	recompile. If the driver load fails to enable a specific interrupt mode, the
	driver will try other interrupt modes, from least to most compatible. The
	interrupt order is MSI-X, MSI, Legacy. If specifying MSI (IntMode=1)
	interrupts, only MSI and Legacy will be attempted.

	CrcStripping
	------------
	Valid Range: 0-1
	Default Value: 1 (enabled)

	Strip the CRC from received packets before sending up the network stack. If
	you have a machine with a BMC enabled but cannot receive IPMI traffic after
	loading or enabling the driver, try disabling this feature.

	WriteProtectNVM
	---------------
	Valid Range: 0,1
	Default Value: 1

	If set to 1, configure the hardware to ignore all write/erase cycles to the
	GbE region in the ICHx NVM (in order to prevent accidental corruption of the
	NVM). This feature can be disabled by setting the parameter to 0 during initial
	driver load.
	NOTE: The machine must be power cycled (full off/on) when enabling NVM writes
	via setting the parameter to zero. Once the NVM has been locked (via the
	parameter at 1 when the driver loads) it cannot be unlocked except via power
	cycle.

	Additional Configurations
	=========================

	Jumbo Frames
	------------
	Jumbo Frames support is enabled by changing the MTU to a value larger than
	the default of 1500. Use the ifconfig command to increase the MTU size.
	For example:

	ifconfig eth<x> mtu 9000 up

	This setting is not saved across reboots.

	Notes:

	- The maximum MTU setting for Jumbo Frames is 9216. This value coincides
	with the maximum Jumbo Frames size of 9234 bytes.

	- Using Jumbo frames at 10 or 100 Mbps is not supported and may result in
	poor performance or loss of link.

	- Some adapters limit Jumbo Frames sized packets to a maximum of
	4096 bytes and some adapters do not support Jumbo Frames.

	- Jumbo Frames cannot be configured on an 82579-based Network device, if
	MACSec is enabled on the system.

	ethtool
	-------
	The driver utilizes the ethtool interface for driver configuration and
	diagnostics, as well as displaying statistical information. We
	strongly recommend downloading the latest version of ethtool at:

	http://ftp.kernel.org/pub/software/network/ethtool/

	NOTE: When validating enable/disable tests on some parts (82578, for example)
	you need to add a few seconds between tests when working with ethtool.

	Speed and Duplex
	----------------
	Speed and Duplex are configured through the ethtool* utility. For
	instructions, refer to the ethtool man page.

	Enabling Wake on LAN* (WoL)
	---------------------------
	WoL is configured through the ethtool* utility. For instructions on
	enabling WoL with ethtool, refer to the ethtool man page.

	WoL will be enabled on the system during the next shut down or reboot.
	For this driver version, in order to enable WoL, the e1000e driver must be
	loaded when shutting down or rebooting the system.

	In most cases Wake On LAN is only supported on port A for multiple port
	adapters. To verify if a port supports Wake on Lan run ethtool eth<X>.

	Support
	=======

	For general information, go to the Intel support website at:

	www.intel.com/support/

	or the Intel Wired Networking project hosted by Sourceforge at:

	http://sourceforge.net/projects/e1000

	If an issue is identified with the released source code on the supported
	kernel with a supported adapter, email the specific information related
	to the issue to e1000-devel@lists.sf.net